novel approaches to expression and detection of oestrus in dairy cows

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and insulin are all moderate h 2 =0.11 to 0.30, largely due to the influence diet has on these variables (Hayhurst et al., 2007). Inclusion of this data for genetic selection is relevant because of the relationship of these hormones and metabolites to NEBAL and BCS. Circulating levels of these hormones can be included in breeding values and can predict susceptibility to NEBAL and low BCS at calving, early in the animals life, which can impact upon fertility and oestrous expression (Flint et al., 2008). There has been little genetic selection for oestrous expression but several factors seem promising. Milk progesterone, GnRH response and metabolic hormone levels have all been reported to influence oestrous expression and are reported to be heritable. Inclusion of heritable estimates for indicators of strong oestrous expression could aid oestrous detection. 1.6 AIMS & OBJECTIVES Many existing methods of oestrous detection; visual, physiological and automated, have flaws in either their accuracy, efficiency or both, and do not meet the ideal requirements described by Senger (1994). Poor oestrous expression is also a hindrance to effective oestrous detection; less intense, shorter duration (Dransfield et al., 1998) and less than 50% seen in standing oestrus (Dobson et al., 2008). However, due to the multifactorial nature of the control of expression of oestrus it is difficult to identify methods to improve expression. The work described within this thesis focuses on the individual cow variation of oestrous expression. The aim is to improve expression permanently through genetics therefore to improve oestrous detection rates. Ideally 24 hour continuous automated surveillance is required to minimise labour requirements and cost. However a method that can accurately detect reliable signs of oestrus to increase detection rates from 50% to the current target of above 70% is required (DairyCo, 2009). Importantly to improve herd fertility the ideal system for identifying cows in oestrus must detect cows standing to be mounted, the definitive sign of oestrus (Orihuela, 2000) and the period which is most significantly correlated with the time of ovulation (Roelofs et al., 2005) resulting in improved conception rates. Hence there is a need to develop a robust system to identify both cows approaching oestrus and cows in oestrus (standing to be mounted), in real-time to overcome the limitations of earlier systems, in order to maximise pregnancy rates and thus profitability. 48
In summary the objective was to formulate solutions to improve oestrous detection by enhancing expression of oestrus and by developing a novel technology for precise, real-time monitoring to detect cows in oestrus. Aims of this work were to: Investigate cow factors that affect expression of oestrus measured by a current automated method of oestrous detection. Investigate individual cow factors such as genetic variation that may affect the expression of oestrus. Develop novel positioning technology to detect oestrus. The aim was to monitor 3 dimensional cows positioning to detect cows approaching oestrus and cows in oestrus. 49
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NOVEL APPROACHES TO EXPRESSION AND
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TABLE OF CONTENTS TABLE OF CONTENTS
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2.2.3 Statistical Analyses ........
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5.3 RESULTS .......................
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Furthermore, automated software was
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LIST OF FIGURES Figure 1.1 Hormonal
Page 13 and 14: LIST OF TABLES Table 1.1 Trends in
Page 15 and 16: LIST OF ABBREVIATIONS ˚ ˚C μM 2D
Page 17 and 18: CHAPTER 1 - Introduction & Literatu
Page 19 and 20: the past 50 years and duration of o
Page 21 and 22: Oestrus growing follicle (Staigmill
Page 23 and 24: ecomes the main inhibitor of FSH an
Page 25 and 26: calf at 40-50 days post partum; inv
Page 27 and 28: al., 2006). However, aged sperm hav
Page 29 and 30: can occur within 2-3 days, but if t
Page 31 and 32: educes the incidence of problem cow
Page 33 and 34: oestradiol, the LH surge and ovulat
Page 35 and 36: The secondary signs of oestrus can
Page 37 and 38: There are also changes in normal be
Page 39 and 40: engage in more natural behaviours i
Page 41 and 42: 1983). Exact explanations and mecha
Page 43 and 44: 2006) and disruption of LH secretio
Page 45 and 46: 1.4.3.2 Milk Yield and Nutrition Di
Page 47 and 48: influence the ability of the ovary
Page 49 and 50: cyclicity can be delayed if dietary
Page 51 and 52: indication for the optimal time to
Page 53 and 54: calving), 3) pre-breeding heat date
Page 55 and 56: 1.5.2 Physiological Changes Physiol
Page 57 and 58: 1.5.2.3 Body and Milk Temperature T
Page 59 and 60: physical activity and stage of the
Page 61 and 62: caused by the general environment t
Page 63: may be gained. This is because data
Page 67 and 68: diet, with concentrates at milking.
Page 69 and 70: oestrus was defined as 3 consecutiv
Page 71 and 72: The interaction between parity and
Page 73 and 74: individual oestrus was not signific
Page 75 and 76: Table 2.4 The effects of the intera
Page 77 and 78: (361 vs. 578 points, respectively,
Page 79 and 80: oestrous expression with increasing
Page 81 and 82: the blood (Sangsritavong et al., 20
Page 83 and 84: CHAPTER 3 - Single Nucleotide Polym
Page 85 and 86: population owing to previous select
Page 87 and 88: Table 3.1 Cont. Follicle Stimulatin
Page 89 and 90: 3.2.4 Sequencing of DNA in the Labo
Page 91 and 92: was achieved. PCR products were rem
Page 93 and 94: 3.4 DISCUSSION The objectives of th
Page 95 and 96: fertility and oestrous expression.
Page 97 and 98: CHAPTER 4 - Development of a Novel
Page 99 and 100: In summary UWB seems a good option
Page 101 and 102: Initial tests were carried out to i
Page 103 and 104: Therefore this demonstrates that X
Page 105 and 106: which is most important for achievi
Page 107 and 108: Figure 4.9 Horizontal - Vertical Di
Page 109 and 110: that UWB is matching the ‘truth
Page 111 and 112: mounting cow. For example height ch
Page 113 and 114: Backpack 1 st put on in AI stalls E
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Cows’ behaviour was assessed at 5
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or that the cows were in an area of
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plane, but mostly in achieving high
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Develop techniques for analysis of
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in elastic silicone moulded over a
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and time of mount, duration of moun
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observed matched with increases in
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5.3 RESULTS Results demonstrate pos
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Figure 5.2 Graph showing mounting b
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Table 5.1 Results from POC 2 showin
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Table 5.3 Efficiency and accuracy o
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oestrus and oestrus it is clear to
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P4 Concentration, ng/ml P4 Concentr
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Page 145 and 146:
Page 147 and 148:
Activity Activity Activity Activity
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5.4 DISCUSSION The aim of this work
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averaged 70% which was lower than t
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when the cows lie down, especially
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the level of oestrous activity was
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technology larger herds must be mon
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monitoring could also monitor non-l
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antennae which could affect accurac
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predispose cows to illness e.g. met
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CHAPTER 6 - Overall Discussion & Co
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oestrus, h 2 =0.27 (Lovendahl et al
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The final section of this thesis de
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ate. By using UWB in a commercial s
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provides an insight the potential o
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BLOWEY, R. (2005) Factors associate
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ovine gonadotrophin releasing hormo
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GINTHER, O. J., KOT, K., KULICK, L.
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associated with embryonic survival
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ody condition at parturition on end
Page 189 and 190:
Signs in a 24-h Tie-Stalled Dairy H
Page 191 and 192:
SHERMAN, E. L., NKRUMAH, J. D., MUR
Page 193 and 194:
Influence of negative energy balanc
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